src/arch/mips/isa.cc - public/gem5 - Git at Google

 /*
  * Copyright (c) 2009 The Regents of The University of Michigan
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met: redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer;
  * redistributions in binary form must reproduce the above copyright
  * notice, this list of conditions and the following disclaimer in the
  * documentation and/or other materials provided with the distribution;
  * neither the name of the copyright holders nor the names of its
  * contributors may be used to endorse or promote products derived from
  * this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "arch/mips/isa.hh"

 #include "arch/mips/mt.hh"
 #include "arch/mips/mt_constants.hh"
 #include "arch/mips/pra_constants.hh"
 #include "arch/mips/regs/float.hh"
 #include "arch/mips/regs/int.hh"
 #include "arch/mips/regs/misc.hh"
 #include "base/bitfield.hh"
 #include "cpu/base.hh"
 #include "cpu/reg_class.hh"
 #include "cpu/thread_context.hh"
 #include "debug/MatRegs.hh"
 #include "debug/MipsPRA.hh"
 #include "params/MipsISA.hh"

 namespace gem5
 {

 namespace MipsISA
 {

 std::string
 ISA::miscRegNames[misc_reg::NumRegs] =
 {
     "Index", "MVPControl", "MVPConf0", "MVPConf1", "", "", "", "",
     "Random", "VPEControl", "VPEConf0", "VPEConf1",
         "YQMask", "VPESchedule", "VPEScheFBack", "VPEOpt",
     "EntryLo0", "TCStatus", "TCBind", "TCRestart",
         "TCHalt", "TCContext", "TCSchedule", "TCScheFBack",
     "EntryLo1", "", "", "", "", "", "", "",
     "Context", "ContextConfig", "", "", "", "", "", "",
     "PageMask", "PageGrain", "", "", "", "", "", "",
     "Wired", "SRSConf0", "SRCConf1", "SRSConf2",
         "SRSConf3", "SRSConf4", "", "",
     "HWREna", "", "", "", "", "", "", "",
     "BadVAddr", "", "", "", "", "", "", "",
     "Count", "", "", "", "", "", "", "",
     "EntryHi", "", "", "", "", "", "", "",
     "Compare", "", "", "", "", "", "", "",
     "Status", "IntCtl", "SRSCtl", "SRSMap", "", "", "", "",
     "Cause", "", "", "", "", "", "", "",
     "EPC", "", "", "", "", "", "", "",
     "PRId", "EBase", "", "", "", "", "", "",
     "Config", "Config1", "Config2", "Config3", "", "", "", "",
     "LLAddr", "", "", "", "", "", "", "",
     "WatchLo0", "WatchLo1", "WatchLo2", "WatchLo3",
         "WatchLo4", "WatchLo5", "WatchLo6", "WatchLo7",
     "WatchHi0", "WatchHi1", "WatchHi2", "WatchHi3",
         "WatchHi4", "WatchHi5", "WatchHi6", "WatchHi7",
     "XCContext64", "", "", "", "", "", "", "",
     "", "", "", "", "", "", "", "",
     "", "", "", "", "", "", "", "",
     "Debug", "TraceControl1", "TraceControl2", "UserTraceData",
         "TraceBPC", "", "", "",
     "DEPC", "", "", "", "", "", "", "",
     "PerfCnt0", "PerfCnt1", "PerfCnt2", "PerfCnt3",
         "PerfCnt4", "PerfCnt5", "PerfCnt6", "PerfCnt7",
     "ErrCtl", "", "", "", "", "", "", "",
     "CacheErr0", "CacheErr1", "CacheErr2", "CacheErr3", "", "", "", "",
     "TagLo0", "DataLo1", "TagLo2", "DataLo3",
         "TagLo4", "DataLo5", "TagLo6", "DataLo7",
     "TagHi0", "DataHi1", "TagHi2", "DataHi3",
         "TagHi4", "DataHi5", "TagHi6", "DataHi7",
     "ErrorEPC", "", "", "", "", "", "", "",
     "DESAVE", "", "", "", "", "", "", "",
     "LLFlag"
 };

 namespace
 {

 /* Not applicable to MIPS. */
 constexpr RegClass vecRegClass(VecRegClass, VecRegClassName, 1,
         debug::IntRegs);
 constexpr RegClass vecElemClass(VecElemClass, VecElemClassName, 2,
         debug::IntRegs);
 constexpr RegClass vecPredRegClass(VecPredRegClass, VecPredRegClassName, 1,
         debug::IntRegs);
 constexpr RegClass matRegClass(MatRegClass, MatRegClassName, 1, debug::MatRegs);
 constexpr RegClass ccRegClass(CCRegClass, CCRegClassName, 0, debug::IntRegs);

 } // anonymous namespace

 ISA::ISA(const Params &p) : BaseISA(p), numThreads(p.num_threads),
     numVpes(p.num_vpes)
 {
     _regClasses.push_back(&intRegClass);
     _regClasses.push_back(&floatRegClass);
     _regClasses.push_back(&vecRegClass);
     _regClasses.push_back(&vecElemClass);
     _regClasses.push_back(&vecPredRegClass);
     _regClasses.push_back(&matRegClass);
     _regClasses.push_back(&ccRegClass);
     _regClasses.push_back(&miscRegClass);

     miscRegFile.resize(misc_reg::NumRegs);
     bankType.resize(misc_reg::NumRegs);

     for (int i = 0; i < misc_reg::NumRegs; i++) {
         miscRegFile[i].resize(1);
         bankType[i] = perProcessor;
     }

     miscRegFile_WriteMask.resize(misc_reg::NumRegs);

     for (int i = 0; i < misc_reg::NumRegs; i++) {
         miscRegFile_WriteMask[i].push_back(0);
     }

     // Initialize all Per-VPE regs
     uint32_t per_vpe_regs[] = { misc_reg::VpeControl,
                                 misc_reg::VpeConf0, misc_reg::VpeConf1,
                                 misc_reg::Yqmask,
                                 misc_reg::VpeSchedule, misc_reg::VpeSchefback,
                                 misc_reg::VpeOpt, misc_reg::SrsConf0,
                                 misc_reg::SrsConf1, misc_reg::SrsConf2,
                                 misc_reg::SrsConf3, misc_reg::SrsConf4,
                                 misc_reg::Ebase
                               };
     uint32_t num_vpe_regs = sizeof(per_vpe_regs) / 4;
     for (int i = 0; i < num_vpe_regs; i++) {
         if (numVpes > 1) {
             miscRegFile[per_vpe_regs[i]].resize(numVpes);
         }
         bankType[per_vpe_regs[i]] = perVirtProcessor;
     }

     // Initialize all Per-TC regs
     uint32_t per_tc_regs[] = { misc_reg::Status,
                                misc_reg::TcStatus, misc_reg::TcBind,
                                misc_reg::TcRestart, misc_reg::TcHalt,
                                misc_reg::TcContext, misc_reg::TcSchedule,
                                misc_reg::TcSchefback,
                                misc_reg::Debug, misc_reg::Lladdr
                              };
     uint32_t num_tc_regs = sizeof(per_tc_regs) /  4;

     for (int i = 0; i < num_tc_regs; i++) {
         miscRegFile[per_tc_regs[i]].resize(numThreads);
         bankType[per_tc_regs[i]] = perThreadContext;
     }

     clear();
 }

 void
 ISA::clear()
 {
     for (int i = 0; i < misc_reg::NumRegs; i++) {
         for (int j = 0; j < miscRegFile[i].size(); j++)
             miscRegFile[i][j] = 0;

         for (int k = 0; k < miscRegFile_WriteMask[i].size(); k++)
             miscRegFile_WriteMask[i][k] = (long unsigned int)(-1);
     }
 }

 void
 ISA::copyRegsFrom(ThreadContext *src)
 {
     // First loop through the integer registers.
     for (auto &id: intRegClass)
         tc->setReg(id, src->getReg(id));

     // Then loop through the floating point registers.
     for (auto &id: floatRegClass)
         tc->setReg(id, src->getReg(id));

     // Copy misc. registers
     for (int i = 0; i < misc_reg::NumRegs; i++)
         tc->setMiscRegNoEffect(i, src->readMiscRegNoEffect(i));

     // Copy over the PC State
     tc->pcState(src->pcState());
 }


 void
 ISA::configCP()
 {
     DPRINTF(MipsPRA, "Resetting CP0 State with %i TCs and %i VPEs\n",
             numThreads, numVpes);

     CoreSpecific cp;
     panic("CP state must be set before the following code is used");

     // Do Default CP0 initialization HERE

     // Do Initialization for MT cores here (eventually use
     // core_name parameter to toggle this initialization)
     // ===================================================
     DPRINTF(MipsPRA, "Initializing CP0 State.... ");

     PRIdReg procId = readMiscRegNoEffect(misc_reg::Prid);
     procId.coOp = cp.CP0_PRId_CompanyOptions;
     procId.coId = cp.CP0_PRId_CompanyID;
     procId.procId = cp.CP0_PRId_ProcessorID;
     procId.rev = cp.CP0_PRId_Revision;
     setMiscRegNoEffect(misc_reg::Prid, procId);

     // Now, create Write Mask for ProcID register
     RegVal procIDMask = 0; // Read-Only register
     replaceBits(procIDMask, 32, 0, 0);
     setRegMask(misc_reg::Prid, procIDMask);

     // Config
     ConfigReg cfg = readMiscRegNoEffect(misc_reg::Config);
     cfg.be = cp.CP0_Config_BE;
     cfg.at = cp.CP0_Config_AT;
     cfg.ar = cp.CP0_Config_AR;
     cfg.mt = cp.CP0_Config_MT;
     cfg.vi = cp.CP0_Config_VI;
     cfg.m = 1;
     setMiscRegNoEffect(misc_reg::Config, cfg);
     // Now, create Write Mask for Config register
     RegVal cfg_Mask = 0x7FFF0007;
     replaceBits(cfg_Mask, 32, 0, 0);
     setRegMask(misc_reg::Config, cfg_Mask);

     // Config1
     Config1Reg cfg1 = readMiscRegNoEffect(misc_reg::Config1);
     cfg1.mmuSize = cp.CP0_Config1_MMU;
     cfg1.is = cp.CP0_Config1_IS;
     cfg1.il = cp.CP0_Config1_IL;
     cfg1.ia = cp.CP0_Config1_IA;
     cfg1.ds = cp.CP0_Config1_DS;
     cfg1.dl = cp.CP0_Config1_DL;
     cfg1.da = cp.CP0_Config1_DA;
     cfg1.fp = cp.CP0_Config1_FP;
     cfg1.ep = cp.CP0_Config1_EP;
     cfg1.wr = cp.CP0_Config1_WR;
     cfg1.md = cp.CP0_Config1_MD;
     cfg1.c2 = cp.CP0_Config1_C2;
     cfg1.pc = cp.CP0_Config1_PC;
     cfg1.m = cp.CP0_Config1_M;
     setMiscRegNoEffect(misc_reg::Config1, cfg1);
     // Now, create Write Mask for Config register
     RegVal cfg1_Mask = 0; // Read Only Register
     replaceBits(cfg1_Mask, 32,0 , 0);
     setRegMask(misc_reg::Config1, cfg1_Mask);

     // Config2
     Config2Reg cfg2 = readMiscRegNoEffect(misc_reg::Config2);
     cfg2.tu = cp.CP0_Config2_TU;
     cfg2.ts = cp.CP0_Config2_TS;
     cfg2.tl = cp.CP0_Config2_TL;
     cfg2.ta = cp.CP0_Config2_TA;
     cfg2.su = cp.CP0_Config2_SU;
     cfg2.ss = cp.CP0_Config2_SS;
     cfg2.sl = cp.CP0_Config2_SL;
     cfg2.sa = cp.CP0_Config2_SA;
     cfg2.m = cp.CP0_Config2_M;
     setMiscRegNoEffect(misc_reg::Config2, cfg2);
     // Now, create Write Mask for Config register
     RegVal cfg2_Mask = 0x7000F000; // Read Only Register
     replaceBits(cfg2_Mask, 32, 0, 0);
     setRegMask(misc_reg::Config2, cfg2_Mask);

     // Config3
     Config3Reg cfg3 = readMiscRegNoEffect(misc_reg::Config3);
     cfg3.dspp = cp.CP0_Config3_DSPP;
     cfg3.lpa = cp.CP0_Config3_LPA;
     cfg3.veic = cp.CP0_Config3_VEIC;
     cfg3.vint = cp.CP0_Config3_VInt;
     cfg3.sp = cp.CP0_Config3_SP;
     cfg3.mt = cp.CP0_Config3_MT;
     cfg3.sm = cp.CP0_Config3_SM;
     cfg3.tl = cp.CP0_Config3_TL;
     setMiscRegNoEffect(misc_reg::Config3, cfg3);
     // Now, create Write Mask for Config register
     RegVal cfg3_Mask = 0; // Read Only Register
     replaceBits(cfg3_Mask, 32,0 , 0);
     setRegMask(misc_reg::Config3, cfg3_Mask);

     // EBase - CPUNum
     EBaseReg eBase = readMiscRegNoEffect(misc_reg::Ebase);
     eBase.cpuNum = cp.CP0_EBase_CPUNum;
     replaceBits(eBase, 31, 31, 1);
     setMiscRegNoEffect(misc_reg::Ebase, eBase);
     // Now, create Write Mask for Config register
     RegVal EB_Mask = 0x3FFFF000;// Except Exception Base, the
                                  // entire register is read only
     replaceBits(EB_Mask, 32, 0, 0);
     setRegMask(misc_reg::Ebase, EB_Mask);

     // SRS Control - HSS (Highest Shadow Set)
     SRSCtlReg scsCtl = readMiscRegNoEffect(misc_reg::Srsctl);
     scsCtl.hss = cp.CP0_SrsCtl_HSS;
     setMiscRegNoEffect(misc_reg::Srsctl, scsCtl);
     // Now, create Write Mask for the SRS Ctl register
     RegVal SC_Mask = 0x0000F3C0;
     replaceBits(SC_Mask, 32, 0, 0);
     setRegMask(misc_reg::Srsctl, SC_Mask);

     // IntCtl - IPTI, IPPCI
     IntCtlReg intCtl = readMiscRegNoEffect(misc_reg::Intctl);
     intCtl.ipti = cp.CP0_IntCtl_IPTI;
     intCtl.ippci = cp.CP0_IntCtl_IPPCI;
     setMiscRegNoEffect(misc_reg::Intctl, intCtl);
     // Now, create Write Mask for the IntCtl register
     RegVal IC_Mask = 0x000003E0;
     replaceBits(IC_Mask, 32, 0, 0);
     setRegMask(misc_reg::Intctl, IC_Mask);

     // Watch Hi - M - FIXME (More than 1 Watch register)
     WatchHiReg watchHi = readMiscRegNoEffect(misc_reg::Watchhi0);
     watchHi.m = cp.CP0_WatchHi_M;
     setMiscRegNoEffect(misc_reg::Watchhi0, watchHi);
     // Now, create Write Mask for the IntCtl register
     RegVal wh_Mask = 0x7FFF0FFF;
     replaceBits(wh_Mask, 32, 0, 0);
     setRegMask(misc_reg::Watchhi0, wh_Mask);

     // Perf Ctr - M - FIXME (More than 1 PerfCnt Pair)
     PerfCntCtlReg perfCntCtl = readMiscRegNoEffect(misc_reg::Perfcnt0);
     perfCntCtl.m = cp.CP0_PerfCtr_M;
     perfCntCtl.w = cp.CP0_PerfCtr_W;
     setMiscRegNoEffect(misc_reg::Perfcnt0, perfCntCtl);
     // Now, create Write Mask for the IntCtl register
     RegVal pc_Mask = 0x00007FF;
     replaceBits(pc_Mask, 32, 0, 0);
     setRegMask(misc_reg::Perfcnt0, pc_Mask);

     // Random
     setMiscRegNoEffect(misc_reg::Cp0Random, 63);
     // Now, create Write Mask for the IntCtl register
     RegVal random_Mask = 0;
     replaceBits(random_Mask, 32, 0, 0);
     setRegMask(misc_reg::Cp0Random, random_Mask);

     // PageGrain
     PageGrainReg pageGrain = readMiscRegNoEffect(misc_reg::Pagegrain);
     pageGrain.esp = cp.CP0_Config3_SP;
     setMiscRegNoEffect(misc_reg::Pagegrain, pageGrain);
     // Now, create Write Mask for the IntCtl register
     RegVal pg_Mask = 0x10000000;
     replaceBits(pg_Mask, 32, 0, 0);
     setRegMask(misc_reg::Pagegrain, pg_Mask);

     // Status
     StatusReg status = readMiscRegNoEffect(misc_reg::Status);
     // Only CU0 and IE are modified on a reset - everything else needs
     // to be controlled on a per CPU model basis

     // Enable CP0 on reset
     // status.cu0 = 1;

     // Enable ERL bit on a reset
     status.erl = 1;
     // Enable BEV bit on a reset
     status.bev = 1;

     setMiscRegNoEffect(misc_reg::Status, status);
     // Now, create Write Mask for the Status register
     RegVal stat_Mask = 0xFF78FF17;
     replaceBits(stat_Mask, 32, 0, 0);
     setRegMask(misc_reg::Status, stat_Mask);


     // MVPConf0
     MVPConf0Reg mvpConf0 = readMiscRegNoEffect(misc_reg::MvpConf0);
     mvpConf0.tca = 1;
     mvpConf0.pvpe = numVpes - 1;
     mvpConf0.ptc = numThreads - 1;
     setMiscRegNoEffect(misc_reg::MvpConf0, mvpConf0);

     // VPEConf0
     VPEConf0Reg vpeConf0 = readMiscRegNoEffect(misc_reg::VpeConf0);
     vpeConf0.mvp = 1;
     setMiscRegNoEffect(misc_reg::VpeConf0, vpeConf0);

     // TCBind
     for (ThreadID tid = 0; tid < numThreads; tid++) {
         TCBindReg tcBind = readMiscRegNoEffect(misc_reg::TcBind, tid);
         tcBind.curTC = tid;
         setMiscRegNoEffect(misc_reg::TcBind, tcBind, tid);
     }
     // TCHalt
     TCHaltReg tcHalt = readMiscRegNoEffect(misc_reg::TcHalt);
     tcHalt.h = 0;
     setMiscRegNoEffect(misc_reg::TcHalt, tcHalt);

     // TCStatus
     // Set TCStatus Activated to 1 for the initial thread that is running
     TCStatusReg tcStatus = readMiscRegNoEffect(misc_reg::TcStatus);
     tcStatus.a = 1;
     setMiscRegNoEffect(misc_reg::TcStatus, tcStatus);

     // Set Dynamically Allocatable bit to 1 for all other threads
     for (ThreadID tid = 1; tid < numThreads; tid++) {
         tcStatus = readMiscRegNoEffect(misc_reg::TcStatus, tid);
         tcStatus.da = 1;
         setMiscRegNoEffect(misc_reg::TcStatus, tcStatus, tid);
     }


     RegVal mask = 0x7FFFFFFF;

     // Now, create Write Mask for the Index register
     replaceBits(mask, 32, 0, 0);
     setRegMask(misc_reg::Index, mask);

     mask = 0x3FFFFFFF;
     replaceBits(mask, 32, 0, 0);
     setRegMask(misc_reg::Entrylo0, mask);
     setRegMask(misc_reg::Entrylo1, mask);

     mask = 0xFF800000;
     replaceBits(mask, 32, 0, 0);
     setRegMask(misc_reg::Context, mask);

     mask = 0x1FFFF800;
     replaceBits(mask, 32, 0, 0);
     setRegMask(misc_reg::Pagemask, mask);

     mask = 0x0;
     replaceBits(mask, 32, 0, 0);
     setRegMask(misc_reg::Badvaddr, mask);
     setRegMask(misc_reg::Lladdr, mask);

     mask = 0x08C00300;
     replaceBits(mask, 32, 0, 0);
     setRegMask(misc_reg::Cause, mask);

 }

 inline unsigned
 ISA::getVPENum(ThreadID tid) const
 {
     TCBindReg tcBind = miscRegFile[misc_reg::TcBind][tid];
     return tcBind.curVPE;
 }

 RegVal
 ISA::readMiscRegNoEffect(RegIndex idx, ThreadID tid) const
 {
     unsigned reg_sel = (bankType[idx] == perThreadContext)
         ? tid : getVPENum(tid);
     DPRINTF(MipsPRA, "Reading CP0 Register:%u Select:%u (%s) (%lx).\n",
             idx / 8, idx % 8, miscRegNames[idx], miscRegFile[idx][reg_sel]);
     return miscRegFile[idx][reg_sel];
 }

 //@TODO: MIPS MT's register view automatically connects
 //       Status to TCStatus depending on current thread
 //template <class TC>
 RegVal
 ISA::readMiscReg(RegIndex idx, ThreadID tid)
 {
     unsigned reg_sel = (bankType[idx] == perThreadContext)
         ? tid : getVPENum(tid);
     DPRINTF(MipsPRA,
             "Reading CP0 Register:%u Select:%u (%s) with effect (%lx).\n",
             idx / 8, idx % 8, miscRegNames[idx], miscRegFile[idx][reg_sel]);

     return miscRegFile[idx][reg_sel];
 }

 void
 ISA::setMiscRegNoEffect(RegIndex idx, RegVal val, ThreadID tid)
 {
     unsigned reg_sel = (bankType[idx] == perThreadContext)
         ? tid : getVPENum(tid);
     DPRINTF(MipsPRA,
             "[tid:%i] Setting (direct set) CP0 Register:%u "
             "Select:%u (%s) to %#x.\n",
             tid, idx / 8, idx % 8, miscRegNames[idx], val);

     miscRegFile[idx][reg_sel] = val;
 }

 void
 ISA::setRegMask(RegIndex idx, RegVal val, ThreadID tid)
 {
     unsigned reg_sel = (bankType[idx] == perThreadContext)
         ? tid : getVPENum(tid);
     DPRINTF(MipsPRA,
             "[tid:%i] Setting CP0 Register: %u Select: %u (%s) to %#x\n",
             tid, idx / 8, idx % 8, miscRegNames[idx], val);
     miscRegFile_WriteMask[idx][reg_sel] = val;
 }

 // PROGRAMMER'S NOTES:
 // (1) Some CP0 Registers have fields that cannot
 // be overwritten. Make sure to handle those particular registers
 // with care!
 void
 ISA::setMiscReg(RegIndex idx, RegVal val, ThreadID tid)
 {
     int reg_sel = (bankType[idx] == perThreadContext)
         ? tid : getVPENum(tid);

     DPRINTF(MipsPRA,
             "[tid:%i] Setting CP0 Register:%u "
             "Select:%u (%s) to %#x, with effect.\n",
             tid, idx / 8, idx % 8, miscRegNames[idx], val);

     RegVal cp0_val = filterCP0Write(idx, reg_sel, val);

     miscRegFile[idx][reg_sel] = cp0_val;

     scheduleCP0Update(tc->getCpuPtr(), Cycles(1));
 }

 /**
  * This method doesn't need to adjust the Control Register Offset
  * since it has already been done in the calling method
  * (setRegWithEffect)
 */
 RegVal
 ISA::filterCP0Write(RegIndex idx, int reg_sel, RegVal val)
 {
     RegVal retVal = val;

     // Mask off read-only regions
     retVal &= miscRegFile_WriteMask[idx][reg_sel];
     RegVal curVal = miscRegFile[idx][reg_sel];
     // Mask off current alue with inverse mask (clear writeable bits)
     curVal &= (~miscRegFile_WriteMask[idx][reg_sel]);
     retVal |= curVal; // Combine the two
     DPRINTF(MipsPRA,
             "filterCP0Write: Mask: %lx, Inverse Mask: %lx, write Val: %x, "
             "current val: %lx, written val: %x\n",
             miscRegFile_WriteMask[idx][reg_sel],
             ~miscRegFile_WriteMask[idx][reg_sel],
             val, miscRegFile[idx][reg_sel], retVal);
     return retVal;
 }

 void
 ISA::scheduleCP0Update(BaseCPU *cpu, Cycles delay)
 {
     if (!cp0Updated) {
         cp0Updated = true;

         //schedule UPDATE
         auto cp0_event = new EventFunctionWrapper(
             [this, cpu]{ processCP0Event(cpu, UpdateCP0); },
             "Coprocessor-0 event", true, Event::CPU_Tick_Pri);
         cpu->schedule(cp0_event, cpu->clockEdge(delay));
     }
 }

 void
 ISA::updateCPU(BaseCPU *cpu)
 {
     ///////////////////////////////////////////////////////////////////
     //
     // EVALUATE CP0 STATE FOR MIPS MT
     //
     ///////////////////////////////////////////////////////////////////
     MVPConf0Reg mvpConf0 = readMiscRegNoEffect(misc_reg::MvpConf0);
     ThreadID num_threads = mvpConf0.ptc + 1;

     for (ThreadID tid = 0; tid < num_threads; tid++) {
         TCStatusReg tcStatus = readMiscRegNoEffect(misc_reg::TcStatus, tid);
         TCHaltReg tcHalt = readMiscRegNoEffect(misc_reg::TcHalt, tid);

         //@todo: add vpe/mt check here thru mvpcontrol & vpecontrol regs
         if (tcHalt.h == 1 || tcStatus.a == 0)  {
             haltThread(cpu->getContext(tid));
         } else if (tcHalt.h == 0 && tcStatus.a == 1) {
             restoreThread(cpu->getContext(tid));
         }
     }

     num_threads = mvpConf0.ptc + 1;

     // Toggle update flag after we finished updating
     cp0Updated = false;
 }

 void
 ISA::processCP0Event(BaseCPU *cpu, CP0EventType cp0EventType)
 {
     switch (cp0EventType)
     {
       case UpdateCP0:
         updateCPU(cpu);
         break;
     }
 }

 } // namespace MipsISA
 } // namespace gem5
	/*
	* Copyright (c) 2009 The Regents of The University of Michigan
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are
	* met: redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer;
	* redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution;
	* neither the name of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "arch/mips/isa.hh"

	#include "arch/mips/mt.hh"
	#include "arch/mips/mt_constants.hh"
	#include "arch/mips/pra_constants.hh"
	#include "arch/mips/regs/float.hh"
	#include "arch/mips/regs/int.hh"
	#include "arch/mips/regs/misc.hh"
	#include "base/bitfield.hh"
	#include "cpu/base.hh"
	#include "cpu/reg_class.hh"
	#include "cpu/thread_context.hh"
	#include "debug/MatRegs.hh"
	#include "debug/MipsPRA.hh"
	#include "params/MipsISA.hh"

	namespace gem5
	{

	namespace MipsISA
	{

	std::string
	ISA::miscRegNames[misc_reg::NumRegs] =
	{
	"Index", "MVPControl", "MVPConf0", "MVPConf1", "", "", "", "",
	"Random", "VPEControl", "VPEConf0", "VPEConf1",
	"YQMask", "VPESchedule", "VPEScheFBack", "VPEOpt",
	"EntryLo0", "TCStatus", "TCBind", "TCRestart",
	"TCHalt", "TCContext", "TCSchedule", "TCScheFBack",
	"EntryLo1", "", "", "", "", "", "", "",
	"Context", "ContextConfig", "", "", "", "", "", "",
	"PageMask", "PageGrain", "", "", "", "", "", "",
	"Wired", "SRSConf0", "SRCConf1", "SRSConf2",
	"SRSConf3", "SRSConf4", "", "",
	"HWREna", "", "", "", "", "", "", "",
	"BadVAddr", "", "", "", "", "", "", "",
	"Count", "", "", "", "", "", "", "",
	"EntryHi", "", "", "", "", "", "", "",
	"Compare", "", "", "", "", "", "", "",
	"Status", "IntCtl", "SRSCtl", "SRSMap", "", "", "", "",
	"Cause", "", "", "", "", "", "", "",
	"EPC", "", "", "", "", "", "", "",
	"PRId", "EBase", "", "", "", "", "", "",
	"Config", "Config1", "Config2", "Config3", "", "", "", "",
	"LLAddr", "", "", "", "", "", "", "",
	"WatchLo0", "WatchLo1", "WatchLo2", "WatchLo3",
	"WatchLo4", "WatchLo5", "WatchLo6", "WatchLo7",
	"WatchHi0", "WatchHi1", "WatchHi2", "WatchHi3",
	"WatchHi4", "WatchHi5", "WatchHi6", "WatchHi7",
	"XCContext64", "", "", "", "", "", "", "",
	"", "", "", "", "", "", "", "",
	"", "", "", "", "", "", "", "",
	"Debug", "TraceControl1", "TraceControl2", "UserTraceData",
	"TraceBPC", "", "", "",
	"DEPC", "", "", "", "", "", "", "",
	"PerfCnt0", "PerfCnt1", "PerfCnt2", "PerfCnt3",
	"PerfCnt4", "PerfCnt5", "PerfCnt6", "PerfCnt7",
	"ErrCtl", "", "", "", "", "", "", "",
	"CacheErr0", "CacheErr1", "CacheErr2", "CacheErr3", "", "", "", "",
	"TagLo0", "DataLo1", "TagLo2", "DataLo3",
	"TagLo4", "DataLo5", "TagLo6", "DataLo7",
	"TagHi0", "DataHi1", "TagHi2", "DataHi3",
	"TagHi4", "DataHi5", "TagHi6", "DataHi7",
	"ErrorEPC", "", "", "", "", "", "", "",
	"DESAVE", "", "", "", "", "", "", "",
	"LLFlag"
	};

	namespace
	{

	/* Not applicable to MIPS. */
	constexpr RegClass vecRegClass(VecRegClass, VecRegClassName, 1,
	debug::IntRegs);
	constexpr RegClass vecElemClass(VecElemClass, VecElemClassName, 2,
	debug::IntRegs);
	constexpr RegClass vecPredRegClass(VecPredRegClass, VecPredRegClassName, 1,
	debug::IntRegs);
	constexpr RegClass matRegClass(MatRegClass, MatRegClassName, 1, debug::MatRegs);
	constexpr RegClass ccRegClass(CCRegClass, CCRegClassName, 0, debug::IntRegs);

	} // anonymous namespace

	ISA::ISA(const Params &p) : BaseISA(p), numThreads(p.num_threads),
	numVpes(p.num_vpes)
	{
	_regClasses.push_back(&intRegClass);
	_regClasses.push_back(&floatRegClass);
	_regClasses.push_back(&vecRegClass);
	_regClasses.push_back(&vecElemClass);
	_regClasses.push_back(&vecPredRegClass);
	_regClasses.push_back(&matRegClass);
	_regClasses.push_back(&ccRegClass);
	_regClasses.push_back(&miscRegClass);

	miscRegFile.resize(misc_reg::NumRegs);
	bankType.resize(misc_reg::NumRegs);

	for (int i = 0; i < misc_reg::NumRegs; i++) {
	miscRegFile[i].resize(1);
	bankType[i] = perProcessor;
	}

	miscRegFile_WriteMask.resize(misc_reg::NumRegs);

	for (int i = 0; i < misc_reg::NumRegs; i++) {
	miscRegFile_WriteMask[i].push_back(0);
	}

	// Initialize all Per-VPE regs
	uint32_t per_vpe_regs[] = { misc_reg::VpeControl,
	misc_reg::VpeConf0, misc_reg::VpeConf1,
	misc_reg::Yqmask,
	misc_reg::VpeSchedule, misc_reg::VpeSchefback,
	misc_reg::VpeOpt, misc_reg::SrsConf0,
	misc_reg::SrsConf1, misc_reg::SrsConf2,
	misc_reg::SrsConf3, misc_reg::SrsConf4,
	misc_reg::Ebase
	};
	uint32_t num_vpe_regs = sizeof(per_vpe_regs) / 4;
	for (int i = 0; i < num_vpe_regs; i++) {
	if (numVpes > 1) {
	miscRegFile[per_vpe_regs[i]].resize(numVpes);
	}
	bankType[per_vpe_regs[i]] = perVirtProcessor;
	}

	// Initialize all Per-TC regs
	uint32_t per_tc_regs[] = { misc_reg::Status,
	misc_reg::TcStatus, misc_reg::TcBind,
	misc_reg::TcRestart, misc_reg::TcHalt,
	misc_reg::TcContext, misc_reg::TcSchedule,
	misc_reg::TcSchefback,
	misc_reg::Debug, misc_reg::Lladdr
	};
	uint32_t num_tc_regs = sizeof(per_tc_regs) / 4;

	for (int i = 0; i < num_tc_regs; i++) {
	miscRegFile[per_tc_regs[i]].resize(numThreads);
	bankType[per_tc_regs[i]] = perThreadContext;
	}

	clear();
	}

	void
	ISA::clear()
	{
	for (int i = 0; i < misc_reg::NumRegs; i++) {
	for (int j = 0; j < miscRegFile[i].size(); j++)
	miscRegFile[i][j] = 0;

	for (int k = 0; k < miscRegFile_WriteMask[i].size(); k++)
	miscRegFile_WriteMask[i][k] = (long unsigned int)(-1);
	}
	}

	void
	ISA::copyRegsFrom(ThreadContext *src)
	{
	// First loop through the integer registers.
	for (auto &id: intRegClass)
	tc->setReg(id, src->getReg(id));

	// Then loop through the floating point registers.
	for (auto &id: floatRegClass)
	tc->setReg(id, src->getReg(id));

	// Copy misc. registers
	for (int i = 0; i < misc_reg::NumRegs; i++)
	tc->setMiscRegNoEffect(i, src->readMiscRegNoEffect(i));

	// Copy over the PC State
	tc->pcState(src->pcState());
	}


	void
	ISA::configCP()
	{
	DPRINTF(MipsPRA, "Resetting CP0 State with %i TCs and %i VPEs\n",
	numThreads, numVpes);

	CoreSpecific cp;
	panic("CP state must be set before the following code is used");

	// Do Default CP0 initialization HERE

	// Do Initialization for MT cores here (eventually use
	// core_name parameter to toggle this initialization)
	// ===================================================
	DPRINTF(MipsPRA, "Initializing CP0 State.... ");

	PRIdReg procId = readMiscRegNoEffect(misc_reg::Prid);
	procId.coOp = cp.CP0_PRId_CompanyOptions;
	procId.coId = cp.CP0_PRId_CompanyID;
	procId.procId = cp.CP0_PRId_ProcessorID;
	procId.rev = cp.CP0_PRId_Revision;
	setMiscRegNoEffect(misc_reg::Prid, procId);

	// Now, create Write Mask for ProcID register
	RegVal procIDMask = 0; // Read-Only register
	replaceBits(procIDMask, 32, 0, 0);
	setRegMask(misc_reg::Prid, procIDMask);

	// Config
	ConfigReg cfg = readMiscRegNoEffect(misc_reg::Config);
	cfg.be = cp.CP0_Config_BE;
	cfg.at = cp.CP0_Config_AT;
	cfg.ar = cp.CP0_Config_AR;
	cfg.mt = cp.CP0_Config_MT;
	cfg.vi = cp.CP0_Config_VI;
	cfg.m = 1;
	setMiscRegNoEffect(misc_reg::Config, cfg);
	// Now, create Write Mask for Config register
	RegVal cfg_Mask = 0x7FFF0007;
	replaceBits(cfg_Mask, 32, 0, 0);
	setRegMask(misc_reg::Config, cfg_Mask);

	// Config1
	Config1Reg cfg1 = readMiscRegNoEffect(misc_reg::Config1);
	cfg1.mmuSize = cp.CP0_Config1_MMU;
	cfg1.is = cp.CP0_Config1_IS;
	cfg1.il = cp.CP0_Config1_IL;
	cfg1.ia = cp.CP0_Config1_IA;
	cfg1.ds = cp.CP0_Config1_DS;
	cfg1.dl = cp.CP0_Config1_DL;
	cfg1.da = cp.CP0_Config1_DA;
	cfg1.fp = cp.CP0_Config1_FP;
	cfg1.ep = cp.CP0_Config1_EP;
	cfg1.wr = cp.CP0_Config1_WR;
	cfg1.md = cp.CP0_Config1_MD;
	cfg1.c2 = cp.CP0_Config1_C2;
	cfg1.pc = cp.CP0_Config1_PC;
	cfg1.m = cp.CP0_Config1_M;
	setMiscRegNoEffect(misc_reg::Config1, cfg1);
	// Now, create Write Mask for Config register
	RegVal cfg1_Mask = 0; // Read Only Register
	replaceBits(cfg1_Mask, 32,0 , 0);
	setRegMask(misc_reg::Config1, cfg1_Mask);

	// Config2
	Config2Reg cfg2 = readMiscRegNoEffect(misc_reg::Config2);
	cfg2.tu = cp.CP0_Config2_TU;
	cfg2.ts = cp.CP0_Config2_TS;
	cfg2.tl = cp.CP0_Config2_TL;
	cfg2.ta = cp.CP0_Config2_TA;
	cfg2.su = cp.CP0_Config2_SU;
	cfg2.ss = cp.CP0_Config2_SS;
	cfg2.sl = cp.CP0_Config2_SL;
	cfg2.sa = cp.CP0_Config2_SA;
	cfg2.m = cp.CP0_Config2_M;
	setMiscRegNoEffect(misc_reg::Config2, cfg2);
	// Now, create Write Mask for Config register
	RegVal cfg2_Mask = 0x7000F000; // Read Only Register
	replaceBits(cfg2_Mask, 32, 0, 0);
	setRegMask(misc_reg::Config2, cfg2_Mask);

	// Config3
	Config3Reg cfg3 = readMiscRegNoEffect(misc_reg::Config3);
	cfg3.dspp = cp.CP0_Config3_DSPP;
	cfg3.lpa = cp.CP0_Config3_LPA;
	cfg3.veic = cp.CP0_Config3_VEIC;
	cfg3.vint = cp.CP0_Config3_VInt;
	cfg3.sp = cp.CP0_Config3_SP;
	cfg3.mt = cp.CP0_Config3_MT;
	cfg3.sm = cp.CP0_Config3_SM;
	cfg3.tl = cp.CP0_Config3_TL;
	setMiscRegNoEffect(misc_reg::Config3, cfg3);
	// Now, create Write Mask for Config register
	RegVal cfg3_Mask = 0; // Read Only Register
	replaceBits(cfg3_Mask, 32,0 , 0);
	setRegMask(misc_reg::Config3, cfg3_Mask);

	// EBase - CPUNum
	EBaseReg eBase = readMiscRegNoEffect(misc_reg::Ebase);
	eBase.cpuNum = cp.CP0_EBase_CPUNum;
	replaceBits(eBase, 31, 31, 1);
	setMiscRegNoEffect(misc_reg::Ebase, eBase);
	// Now, create Write Mask for Config register
	RegVal EB_Mask = 0x3FFFF000;// Except Exception Base, the
	// entire register is read only
	replaceBits(EB_Mask, 32, 0, 0);
	setRegMask(misc_reg::Ebase, EB_Mask);

	// SRS Control - HSS (Highest Shadow Set)
	SRSCtlReg scsCtl = readMiscRegNoEffect(misc_reg::Srsctl);
	scsCtl.hss = cp.CP0_SrsCtl_HSS;
	setMiscRegNoEffect(misc_reg::Srsctl, scsCtl);
	// Now, create Write Mask for the SRS Ctl register
	RegVal SC_Mask = 0x0000F3C0;
	replaceBits(SC_Mask, 32, 0, 0);
	setRegMask(misc_reg::Srsctl, SC_Mask);

	// IntCtl - IPTI, IPPCI
	IntCtlReg intCtl = readMiscRegNoEffect(misc_reg::Intctl);
	intCtl.ipti = cp.CP0_IntCtl_IPTI;
	intCtl.ippci = cp.CP0_IntCtl_IPPCI;
	setMiscRegNoEffect(misc_reg::Intctl, intCtl);
	// Now, create Write Mask for the IntCtl register
	RegVal IC_Mask = 0x000003E0;
	replaceBits(IC_Mask, 32, 0, 0);
	setRegMask(misc_reg::Intctl, IC_Mask);

	// Watch Hi - M - FIXME (More than 1 Watch register)
	WatchHiReg watchHi = readMiscRegNoEffect(misc_reg::Watchhi0);
	watchHi.m = cp.CP0_WatchHi_M;
	setMiscRegNoEffect(misc_reg::Watchhi0, watchHi);
	// Now, create Write Mask for the IntCtl register
	RegVal wh_Mask = 0x7FFF0FFF;
	replaceBits(wh_Mask, 32, 0, 0);
	setRegMask(misc_reg::Watchhi0, wh_Mask);

	// Perf Ctr - M - FIXME (More than 1 PerfCnt Pair)
	PerfCntCtlReg perfCntCtl = readMiscRegNoEffect(misc_reg::Perfcnt0);
	perfCntCtl.m = cp.CP0_PerfCtr_M;
	perfCntCtl.w = cp.CP0_PerfCtr_W;
	setMiscRegNoEffect(misc_reg::Perfcnt0, perfCntCtl);
	// Now, create Write Mask for the IntCtl register
	RegVal pc_Mask = 0x00007FF;
	replaceBits(pc_Mask, 32, 0, 0);
	setRegMask(misc_reg::Perfcnt0, pc_Mask);

	// Random
	setMiscRegNoEffect(misc_reg::Cp0Random, 63);
	// Now, create Write Mask for the IntCtl register
	RegVal random_Mask = 0;
	replaceBits(random_Mask, 32, 0, 0);
	setRegMask(misc_reg::Cp0Random, random_Mask);

	// PageGrain
	PageGrainReg pageGrain = readMiscRegNoEffect(misc_reg::Pagegrain);
	pageGrain.esp = cp.CP0_Config3_SP;
	setMiscRegNoEffect(misc_reg::Pagegrain, pageGrain);
	// Now, create Write Mask for the IntCtl register
	RegVal pg_Mask = 0x10000000;
	replaceBits(pg_Mask, 32, 0, 0);
	setRegMask(misc_reg::Pagegrain, pg_Mask);

	// Status
	StatusReg status = readMiscRegNoEffect(misc_reg::Status);
	// Only CU0 and IE are modified on a reset - everything else needs
	// to be controlled on a per CPU model basis

	// Enable CP0 on reset
	// status.cu0 = 1;

	// Enable ERL bit on a reset
	status.erl = 1;
	// Enable BEV bit on a reset
	status.bev = 1;

	setMiscRegNoEffect(misc_reg::Status, status);
	// Now, create Write Mask for the Status register
	RegVal stat_Mask = 0xFF78FF17;
	replaceBits(stat_Mask, 32, 0, 0);
	setRegMask(misc_reg::Status, stat_Mask);


	// MVPConf0
	MVPConf0Reg mvpConf0 = readMiscRegNoEffect(misc_reg::MvpConf0);
	mvpConf0.tca = 1;
	mvpConf0.pvpe = numVpes - 1;
	mvpConf0.ptc = numThreads - 1;
	setMiscRegNoEffect(misc_reg::MvpConf0, mvpConf0);

	// VPEConf0
	VPEConf0Reg vpeConf0 = readMiscRegNoEffect(misc_reg::VpeConf0);
	vpeConf0.mvp = 1;
	setMiscRegNoEffect(misc_reg::VpeConf0, vpeConf0);

	// TCBind
	for (ThreadID tid = 0; tid < numThreads; tid++) {
	TCBindReg tcBind = readMiscRegNoEffect(misc_reg::TcBind, tid);
	tcBind.curTC = tid;
	setMiscRegNoEffect(misc_reg::TcBind, tcBind, tid);
	}
	// TCHalt
	TCHaltReg tcHalt = readMiscRegNoEffect(misc_reg::TcHalt);
	tcHalt.h = 0;
	setMiscRegNoEffect(misc_reg::TcHalt, tcHalt);

	// TCStatus
	// Set TCStatus Activated to 1 for the initial thread that is running
	TCStatusReg tcStatus = readMiscRegNoEffect(misc_reg::TcStatus);
	tcStatus.a = 1;
	setMiscRegNoEffect(misc_reg::TcStatus, tcStatus);

	// Set Dynamically Allocatable bit to 1 for all other threads
	for (ThreadID tid = 1; tid < numThreads; tid++) {
	tcStatus = readMiscRegNoEffect(misc_reg::TcStatus, tid);
	tcStatus.da = 1;
	setMiscRegNoEffect(misc_reg::TcStatus, tcStatus, tid);
	}


	RegVal mask = 0x7FFFFFFF;

	// Now, create Write Mask for the Index register
	replaceBits(mask, 32, 0, 0);
	setRegMask(misc_reg::Index, mask);

	mask = 0x3FFFFFFF;
	replaceBits(mask, 32, 0, 0);
	setRegMask(misc_reg::Entrylo0, mask);
	setRegMask(misc_reg::Entrylo1, mask);

	mask = 0xFF800000;
	replaceBits(mask, 32, 0, 0);
	setRegMask(misc_reg::Context, mask);

	mask = 0x1FFFF800;
	replaceBits(mask, 32, 0, 0);
	setRegMask(misc_reg::Pagemask, mask);

	mask = 0x0;
	replaceBits(mask, 32, 0, 0);
	setRegMask(misc_reg::Badvaddr, mask);
	setRegMask(misc_reg::Lladdr, mask);

	mask = 0x08C00300;
	replaceBits(mask, 32, 0, 0);
	setRegMask(misc_reg::Cause, mask);

	}

	inline unsigned
	ISA::getVPENum(ThreadID tid) const
	{
	TCBindReg tcBind = miscRegFile[misc_reg::TcBind][tid];
	return tcBind.curVPE;
	}

	RegVal
	ISA::readMiscRegNoEffect(RegIndex idx, ThreadID tid) const
	{
	unsigned reg_sel = (bankType[idx] == perThreadContext)
	? tid : getVPENum(tid);
	DPRINTF(MipsPRA, "Reading CP0 Register:%u Select:%u (%s) (%lx).\n",
	idx / 8, idx % 8, miscRegNames[idx], miscRegFile[idx][reg_sel]);
	return miscRegFile[idx][reg_sel];
	}

	//@TODO: MIPS MT's register view automatically connects
	// Status to TCStatus depending on current thread
	//template <class TC>
	RegVal
	ISA::readMiscReg(RegIndex idx, ThreadID tid)
	{
	unsigned reg_sel = (bankType[idx] == perThreadContext)
	? tid : getVPENum(tid);
	DPRINTF(MipsPRA,
	"Reading CP0 Register:%u Select:%u (%s) with effect (%lx).\n",
	idx / 8, idx % 8, miscRegNames[idx], miscRegFile[idx][reg_sel]);

	return miscRegFile[idx][reg_sel];
	}

	void
	ISA::setMiscRegNoEffect(RegIndex idx, RegVal val, ThreadID tid)
	{
	unsigned reg_sel = (bankType[idx] == perThreadContext)
	? tid : getVPENum(tid);
	DPRINTF(MipsPRA,
	"[tid:%i] Setting (direct set) CP0 Register:%u "
	"Select:%u (%s) to %#x.\n",
	tid, idx / 8, idx % 8, miscRegNames[idx], val);

	miscRegFile[idx][reg_sel] = val;
	}

	void
	ISA::setRegMask(RegIndex idx, RegVal val, ThreadID tid)
	{
	unsigned reg_sel = (bankType[idx] == perThreadContext)
	? tid : getVPENum(tid);
	DPRINTF(MipsPRA,
	"[tid:%i] Setting CP0 Register: %u Select: %u (%s) to %#x\n",
	tid, idx / 8, idx % 8, miscRegNames[idx], val);
	miscRegFile_WriteMask[idx][reg_sel] = val;
	}

	// PROGRAMMER'S NOTES:
	// (1) Some CP0 Registers have fields that cannot
	// be overwritten. Make sure to handle those particular registers
	// with care!
	void
	ISA::setMiscReg(RegIndex idx, RegVal val, ThreadID tid)
	{
	int reg_sel = (bankType[idx] == perThreadContext)
	? tid : getVPENum(tid);

	DPRINTF(MipsPRA,
	"[tid:%i] Setting CP0 Register:%u "
	"Select:%u (%s) to %#x, with effect.\n",
	tid, idx / 8, idx % 8, miscRegNames[idx], val);

	RegVal cp0_val = filterCP0Write(idx, reg_sel, val);

	miscRegFile[idx][reg_sel] = cp0_val;

	scheduleCP0Update(tc->getCpuPtr(), Cycles(1));
	}

	/**
	* This method doesn't need to adjust the Control Register Offset
	* since it has already been done in the calling method
	* (setRegWithEffect)
	*/
	RegVal
	ISA::filterCP0Write(RegIndex idx, int reg_sel, RegVal val)
	{
	RegVal retVal = val;

	// Mask off read-only regions
	retVal &= miscRegFile_WriteMask[idx][reg_sel];
	RegVal curVal = miscRegFile[idx][reg_sel];
	// Mask off current alue with inverse mask (clear writeable bits)
	curVal &= (~miscRegFile_WriteMask[idx][reg_sel]);
	retVal \|= curVal; // Combine the two
	DPRINTF(MipsPRA,
	"filterCP0Write: Mask: %lx, Inverse Mask: %lx, write Val: %x, "
	"current val: %lx, written val: %x\n",
	miscRegFile_WriteMask[idx][reg_sel],
	~miscRegFile_WriteMask[idx][reg_sel],
	val, miscRegFile[idx][reg_sel], retVal);
	return retVal;
	}

	void
	ISA::scheduleCP0Update(BaseCPU *cpu, Cycles delay)
	{
	if (!cp0Updated) {
	cp0Updated = true;

	//schedule UPDATE
	auto cp0_event = new EventFunctionWrapper(
	[this, cpu]{ processCP0Event(cpu, UpdateCP0); },
	"Coprocessor-0 event", true, Event::CPU_Tick_Pri);
	cpu->schedule(cp0_event, cpu->clockEdge(delay));
	}
	}

	void
	ISA::updateCPU(BaseCPU *cpu)
	{
	///////////////////////////////////////////////////////////////////
	//
	// EVALUATE CP0 STATE FOR MIPS MT
	//
	///////////////////////////////////////////////////////////////////
	MVPConf0Reg mvpConf0 = readMiscRegNoEffect(misc_reg::MvpConf0);
	ThreadID num_threads = mvpConf0.ptc + 1;

	for (ThreadID tid = 0; tid < num_threads; tid++) {
	TCStatusReg tcStatus = readMiscRegNoEffect(misc_reg::TcStatus, tid);
	TCHaltReg tcHalt = readMiscRegNoEffect(misc_reg::TcHalt, tid);

	//@todo: add vpe/mt check here thru mvpcontrol & vpecontrol regs
	if (tcHalt.h == 1 \|\| tcStatus.a == 0) {
	haltThread(cpu->getContext(tid));
	} else if (tcHalt.h == 0 && tcStatus.a == 1) {
	restoreThread(cpu->getContext(tid));
	}
	}

	num_threads = mvpConf0.ptc + 1;

	// Toggle update flag after we finished updating
	cp0Updated = false;
	}

	void
	ISA::processCP0Event(BaseCPU *cpu, CP0EventType cp0EventType)
	{
	switch (cp0EventType)
	{
	case UpdateCP0:
	updateCPU(cpu);
	break;
	}
	}

	} // namespace MipsISA
	} // namespace gem5